# NumPy空气污染指数数据如下：
import numpy as np
# Data: air quality index AQI data (row = city)
X = np.array(
    [
        [42, 40, 41, 43, 44, 43],  # Hong Kong
        [30, 31, 29, 29, 29, 30],  # New York
        [8, 13, 31, 11, 11, 9],  # Berlin
        [11, 11, 12, 13, 11, 12]
    ])  # Montreal
cities = np.array(["Hong Kong", "New York", "Berlin", "Montreal"])

# 要找出在平均污染指数之上的城市(任何一次)，应如何操作？


def action():
    return None


def test_action():
    assert action() == {'Hong Kong', 'New York', 'Berlin'}
